This invention concerns fuel rail assemblies for fuel injected internal combustion engines. Modern engines are usually fuel injected, using one or more fuel rails comprised of hollow tubes, which are supplied with pressurized fuel. A series of fuel injectors are mounted along the fuel rails to be able to receive a flow of fuel from a passage within the fuel rails, the fuel injectors comprising solenoid-operated valves which are opened by electronic switching signals received from an electronic engine controller to cause a volume of fuel to be sprayed into the air intake valve opening of a respective engine cylinder.
The valves are operated by a solenoid, energized by the electronic signals transmitted from the engine controller for predetermined time intervals to inject a proper metered volume of fuel for the various engine operating parameters, all in the manner well known in the art.
The valve solenoids each require electrical connections to be made to the electronic controller.
The most common configuration of fuel injectors is an elongated generally cylindrical body mounted to the fuel rail to extend in a direction transverse to the length of the fuel rail. In so called "top feed" injectors, the top of the injector is seated against a port in the fuel rail to admit fuel into the injector.
In top feed, the entire length of the injector projects from the fuel rail, such that the assembly occupies considerable space. In "bottom feed" injectors developed to alleviate this problem, the fuel rail seat surrounds a substantial portion of the length of the injector to shorten the transverse dimension of the fuel rail assembly.
In both injector configurations, an electrical connector is mounted at an intermediate location along the length of the injector external to the fuel rails, with wire leads extending from each connector to the electronic controller.
In bottom feed injectors, the fuel injector projects above the fuel rail, and an electrical connector is provided at this location. A seal is required at the top and bottom of the injector, to increase the manufacturing costs over the top feed design.
Each connector has two leads, a circuit common lead and a "switch" signal lead over which the switching signal for each individual injector is transmitted. These leads must be hermetically sealed from the atmosphere to prevent corrosion and possible development of a faulty electrical connection which can occur over time if the contacts are exposed to the atmosphere. Each connector body must also be sealed from the fuel cavity.
The external routing of the wires requires a wire harness and a cover for the wire leads.
In U.S. Pat. No. 5,178,115 issued on Jan. 12, 1993 for a "Fuel Rail Assembly Having Self-Contained Electronics," there is described a special injector valve which is mounted entirely within the fuel rail, as are the electrical leads and other circuit components for control of the injector. The injector valve utilizes a magnetic circuit operation rather than a solenoid and is sufficiently compact to be housed entirely within the fuel rail.
The present invention seeks to provide an arrangement for conventionally configured elongated cylinder, solenoid-operated fuel injectors which reduces the seals required both for the injector body and the electrical leads by providing connectors which are located entirely within the fuel passage to be isolated from the atmosphere.
Fuel injectors with "air assist" are also known, in which air is supplied to the injectors, which in turn have passages directing the air flow to an injection port so as to impinge the injected fuel, assisting in breaking up the fuel droplets, In these fuel injectors, an air chamber surrounds the lower end of the injector. The external electrical connector for top feed injectors is interposed between the fuel rail and the air chamber. The air chamber must therefore be sealed at its top and bottom joint with the injector as well as to an air manifold supplying compressed air to each chamber.
It is another object of the present invention to provide an electrical connector for air assisted fuel injectors which simplifies the sealing of the air assist chamber.